Process of improved grayscale lithography

Abstract

Methods for minimizing the errors associated with substrate etching are presented. The methods use intentional defocusing of the pattern image on the photoresist to minimize errors in the etching process particularly grayscale etching and/or multiple exposure contributions from neighboring patterns.

1 . A method of decreasing errors associated with etching substrates comprising: 
 providing a first optical device having a range of defocus;    illuminating a mask through said optical device resulting in a focused pattern image on or in a photoresist layer deposited on a substrate; and    intentionally defocusing said pattern image an intentional amount.    
   
   
       2 . The method according to  claim 1 , wherein the defocusing is accomplished by positioning a second optical device between the mask and the photoresist layer, wherein illumination passing through said second optical device results in said pattern image on said photoresist layer that is defocused an intentional amount.  
   
   
       3 . The method according to  claim 1 , further comprising: 
 moving said first optical device to a defocus distance that results in a focused pattern image at a point between the mask and said pattern image.    
   
   
       4 . The method according to  claim 1 , wherein the defocusing is accomplished by intentionally defocusing said first optical device an amount greater than a thickness of said photoresist layer, wherein a focused pattern image is moved away from a surface of the photoresist a predetermined amount.  
   
   
       5 . A micro-lens formed from a process comprising: 
 providing a grayscale mask, wherein said grayscale mask contains a pattern to be etched in a substrate;    generating illumination light passing through said mask and resulting in a pattern image on a photoresist layer deposited on said substrate;    defocusing the pattern image on the photoresist;    developing said photoresist layer with the defocused said pattern image; and    etching said substrate, wherein said etching uses said photoresist layer and produces a curved surface etched into said substrate.    
   
   
       6 . The micro-lens formed according to  claim 5 , wherein defocusing is accomplished by positioning an optical device above said photoresist layer, and wherein said optical device results in said pattern image on said photoresist layer that is defocused an intentional amount.  
   
   
       7 . A method of decreasing errors associated with etching arrays of identical patterns in substrates comprising: 
 providing an illumination device, at a focused position, having a range of defocus; and    generating multiple illuminations of a mask containing multiple patterns, resulting in multiple focused images on a photoresist layer deposited on a substrate, where each of the focused images results from multiple exposures of the multiple patterns.